1. Field of the Invention
The present invention is directed to polyamide-polyether block copolymers and the use of polyamide-polyether block copolymers as gellants for liquids in, for example, air fresheners and personal care products.
2. Description of the Related Art
In many commercially important compositions, the consistency of the product is critical to its commercial success. One example is personal care products, which generally contain one or more active ingredients within a carrier formulation. While the active ingredient(s) determine the ultimate performance utility of the product, the carrier formulation is critical to the commercial success of the product in that it largely determines the consistency of the product. The rheology of the carrier or “base” largely determines the manner in which the consumer will apply or use the product. Many commercial and would-be commercial products depend upon the availability of materials called “gelling agents” that have the ability to modify various rheological properties, in order to allow formulation of a successful product.
Products are often desired to be “gels,” in that they maintain their shape when undisturbed but flow upon being sheared. Transparent gelled carriers are especially desired by formulators who develop products wherein a colorant is an active ingredient, for example in a lipgloss or rouge, because a transparent carrier (as opposed to an opaque carrier) will minimally, if at all, interfere with the appearance of the colorant. In recent years, consumers have demonstrated an increasing preference for transparent and colorless personal care products such as deodorants and shampoos.
The patent literature contains many descriptions of polyamide compositions, processes for their preparation, and their many uses. The following patents list 1,4-cyclohexane dicarboxylic acid (CHDA) as one of the diacid raw materials that may be used to prepare a polyamide.
U.S. Pat. No. 3,950,310 to Bouboulis (1976), discloses polyamides suitable for use as fibers and molding compounds prepared by reacting a dicarboxylic acid with a cyclohexane-bis(beta-ethylamine). While it is mentioned that the diacid can be CHDA, this is not a preferred diacid.
U.S. Pat. No. 4,218,351 to Rasmussen (1980), discloses the preparation of impact resistant, thermoplastic polyamides having about 58 to about 95 mole % short chain diacid moieties. A list of possible diacids is provided, where the list includes any one of the isomers of CHDA. Other compounds used to make the polyamide are 5 to 30 mol % dimer acid, and 0.25 to 12.5 mole % polyamide-forming oligomer, which can be polyether diamines such as JEFFAMINE™ D-2000. The polyamides are stated to be well suited for use as hot melt adhesives, that is, in adhesive formulations containing no organic solvent.
U.S. Pat. No. 4,223,127 Meyer et al. (1980), discloses polyamides suitable for use in forming fibers, films, and molded objects prepared by reacting a lactam and a dicarboxylic acid with a diamino dicyclohexylmethane. One of the listed dicarboxylic acids is CHDA.
U.S. Pat. No. 4,293,668 to Campbell (1981), discloses polyamides useful for making fibers. The polyamides are prepared from 5-methyl-1,9-nonane diamine and CHDA.
U.S. Pat. No. 4,398,012 to Merrill et al. (1983), discloses copolyamides for use as molding compounds prepared by co-reacting a lactam, a cyclic dicarboxylic acid, and a cyclic diamine. The dicarboxylic acid may be CHDA.
U.S. Pat. No. 4,471,088 to Chiba et al. (1984), discloses copolyamides for use as molding compounds with high rigidity and excellent dimensional stability. These copolyamides are prepared by reacting CHDA and a diamine having 11 to 13 carbon atoms.
U.S. Pat. No. 4,921,932 to Tamura et al. (1990), discloses copolyamides useful as molding compounds prepared by reacting a lactam, a dimerized fatty diacid, a monocarboxylic acid, an optional co-diacid which can be CHDA, and a diamine.
U.S. Pat. No. 5,773,558 to Torre (1998), discloses polyamides useful as molding compounds which having high rigidity, solvent resistance, and high heat resistance. These polyamides are prepared by reacting CHDA with an aliphatic diamine.
The following are exemplary U.S. patents that disclose specific polyamides as gelling agents:
U.S. Pat. No. 3,615,289 to Avon Products (1971), discloses compositions suitable for burning as a candle that consist of a polymerized fatty acid polyamide blended with an alkanolamide and a stearic acid ester.
U.S. Pat. No. 3,819,342 to Avon Products (1974), discloses compositions suitable for burning as a candle that consist of a polymerized fatty acid polyamide blended with a fatty alcohol and having what is described as a “gel-type structure.”
U.S. Pat. No. 4,552,693 to Avon Products (1985), discloses compositions suitable for release a fragrance that consist of a polymerized fatty acid polyamide blended with a sulfonamide plasticizer, a fragrance, a surfactant, and a mineral oil. The polyamide comprises 60-65 wt % of the article.
U.S. Pat. No. 5,783,657 to Union Camp Corporation (1998), discloses dimer acid-based polyamide compositions which dissolve in non-polar liquids such as mineral oil and, when cooled to room temperature, form firm, transparent gels. The compositions are specific in requiring that they contain an amount of ester groups and, furthermore, that these esters must be located at the ends of the polymer chain.
U.S. Pat. No. 5,998,570 to Union Camp Corporation (1999), “Ester-Terminated Polyamides Of Polymerized Fatty Acids Useful In Formulating Transparent Gels In Low Polarity Liquids.”
U.S. Pat. No. 5,882,363 to The Noville Corp. (1999), discloses compositions suitable for burning as a candle that consists of about 40-70% by weight of a polyamide blended with a 12-hydroxystearic acid ester. The polyamide is not described in detail but is described as a “gellant” and is selected from two classes; nylon terpolymers (DuPont Elvamides) and those made from dimer acid (Henkel Corp. VERSAMID™ resins or Union Camp Corp. UNI-REZ™ resins).
U.S. Pat. No. 6,111,055 to Union Camp Corporation and Bush Boake Allen (2000), contains disclosure directed to polyamide gelling agents useful in preparing candles, flammable objects, etc.
U.S. Pat. No. 6,268,466 (2001) to Arizona Chemical Company, discloses a dimer-acid polyamide which can dissolve in non-polar liquids such as mineral oil and form transparent gels upon cooling. The compositions are specific in requiring that the polymer chains be terminated with tertiary amide groups.
U.S. Pat. No. 6,399,713 to Arizona Chemical Company (2002) discloses polyamide gelling agents (designated PAOPAs, for poly(alkyleneoxy)-terminated polyamides), consisting of the reaction product of dimer acid, ethylene diamine (EDA), a poly(oxyethylene/propylene)diamine, and a poly(oxyethylene/propylene)monoamine.
Dimer diamine has been described as a component for preparing certain polyamides. For example, U.S. Pat. No. 4,018,731 to Foster Grant Co. (1977), discloses high-impact polyamide resins prepared by reacting an amino carboxylic acid, a lactam, a mixture of a diacid and a diamine, and an amine- or acid-functionalized diolefin polymer.
U.S. Pat. No. 4,018,733 to Raychem Corporation (1977), discloses hot-melt adhesive compositions comprising an acidic ethylene polymer blended with a polyamide. The polyamide is preferably prepared from at least 60% dimer acid and diamine selected from a group of aliphatic diamine including polyether diamines and dimer diamine.
Although certain polyamide resins have the ability to function as gelling agents for organic solvents, there remains a need in the art for compounds that gel liquids, especially polar liquids, to provide gels of varying degrees of hardness and strength, especially at relatively low concentrations of the gelling agent. The present invention is directed to fulfilling this need and provides additional advantages as described more fully herein.